Drug Allergy Symptoms

Overview

Drug allergy
symptoms are effects that happen when you’re allergic to a drug. Taking the
drug triggers your immune system to react. The symptoms of these reactions are
different from other side effects of the drug. They range from
mild to severe, with symptoms of anaphylaxis being the most severe.

Many drug allergies will not cause symptoms the first time
you use the drug. In fact, you may use the drug several times without any
reaction. When a drug does cause a reaction, though, the symptoms usually
appear soon after you take it. And anaphylaxis symptoms usually begin within
moments of taking the drug.

Mild symptoms of drug allergy

During a mild allergic reaction, you may have one or more of
the following symptoms:

skin rash

hives

itchy skin or eyes

fever

joint aches or swelling

tender lymph nodes

Severe symptoms of drug allergy

Severe symptoms often indicate a life-threatening reaction
called anaphylaxis. This reaction affects many of your body’s functions.
Anaphylaxis symptoms include:

tightening of your throat and difficulty breathing

swelling of your lips, mouth, or eyelids

abdominal pain

nausea, vomiting, or diarrhea

dizziness or lightheadedness

confusion

palpitations (rapid or fluttering heartrate)

If you experience any symptoms of a severe reaction to a
drug, you should seek emergency medical care immediately.

When to call your doctor

You should call your doctor any time you have an unexpected
symptom from a drug. Mild allergic symptoms usually stop once you stop taking
the drug. However, you shouldn’t stop taking a drug without talking to your
doctor first.

Your doctor will also need to rule out other possible causes
of your symptoms. Having the doctor see you while you are experiencing a reaction
may help them confirm the cause of your symptoms. It may also help your doctor
determine the best treatment for the reaction or help them choose a different
drug.

Talk to your doctor

Many drugs can cause an allergic reaction. It's important
that your doctor know your complete medical history when prescribing a drug to
you. Make sure you tell your doctor about any allergies you have, including
reactions you’ve had to any medication you took in the past. If you've had an
allergic reaction to a drug, you shouldn’t take that drug again.

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.